I love effect when some element on grayscale photo is highlighted
using bright color, for example lips or eyes color on the face, without
changing element texture. I want to show how to do this in Adobe
Photoshop CS2.

First we will open photo in Photoshop, discolor it using
Image/Adjustments/Desaturate:

Using Polygonal Lasso tool will select area, which will be painted
over, but previously set Feather value to 1px to get avoid sharp edge of
lips:

Now will select Brush tool and set following options:

I choosed following foreground color for the lips: BC2805. Then I painted
over lips and removed selection. We can enlarge brush size and paint
cheeks a little using the same color. We got attractive girl with red
lips: